This application is based on and claims the priority under 35 U.S.C. xc2xa7119 of German Patent Application 100 26 469.7, filed on May 27, 2000, the entire disclosure of which is incorporated herein by reference.
The invention relates to a method of deploying a parachute on a drone air vehicle so as to avoid an uncontrolled crash of the drone.
A drone is an unmanned airborne vehicle for civil or military applications, for example for area reconnaissance. The drone is generally programmed or controlled to land according to plan in a desired location, once its mission is fulfilled. To this effect a control device of the drone activates a parachute system according to a program, so that the parachute system ejects and activates a parachute connected to the drone. The drone lands in the target area by means of the parachute. It is known that the drone can trigger the parachute system by means of a flight control computer and its program, integrated in the control device. There is also the option of triggering the parachute system over the target area by way of remote-controlled signaling to the flight control computer. In all these cases, the landing procedure is planned, i.e. intended.
Apart from the flight control computer, the control system of a drone at least also comprises such subsystems as the hydraulic system, the electrical system, the power supply system, the propulsion system and the control and actuating drive system. These are error-critical subsystems, whereby an individual failure of a subassembly from one of these systems frequently leads to the loss of the drone. In the case of failure, such a drone cannot make an emergency landing. It crashes or self-destructs. Such a case of failure can endanger the immediate surroundings in the area of the crash or destruction of the drone. Furthermore, the operator of the drone will desire far-reaching protection of the drone so as to be able to reuse it after repairing affected subassemblies.
Operators of drones have conventionally attempted to solve the above problems by employing the same design approach as is used for achieving adequate safety in manned airborne vehicles, namely by means of redundant design and provision of the various subsystems of the control system, e.g. providing two propulsion engines, two actuators for each actuating function, etc. This means duplicating all subsystems necessary to maintain proper command and operation of the drone in case of failure of a first one of the respective subsystems, including propulsion, power supply, control, etc. By such duplication, a back-up redundancy of the subsystems is attained. In the case of failure of a subsystem, planned continued operation of the drone is thus ensured by the continued proper operation of the respective second redundant subsystem. However, this solution leads to a drastic increase of the flying weight of the drone, so that a more powerful propulsion system is required. The conventional approach is thus very intensive in materials and costs, both in the original manufacturing and in the ongoing operation of the drone.
In view of the above, it is an object of the invention to make a drone more economical by simplifying its subsystems while in the case of failure nevertheless preventing the drone from crashing in an uncontrolled way, to the extent that this is possible. The invention further aims to avoid or overcome the disadvantages of the prior art, and to achieve additional advantages, as apparent from the present specification.
The above objects have been achieved according to the invention in a drone air vehicle and a method of deploying a parachute from the drone. According to the invention, signals and/or data are supplied from at least flight-relevant subsystems such as the power supply system, the propulsion system and the actuating drive system to an error detection device via signal connections and/or data connections. The error detection device detects errors or error combinations according to a program and then, in response to detecting such an error or error combination, supplies a signal to the parachute system so that the parachute system forms a control signal which causes ejection of the parachute by the ejection mechanism. Thus, if a critical error condition (which would likely lead to lack of control and/or crashing of the drone) is detected, the drone will automatically and self-sufficiently be deactivated and will be carried safely down to the ground or water on the deployed parachute. With the inventive arrangement and method, it is not necessary to provide redundancy of the various systems, i.e. single systems can be provided without backup, because the drone can be safely recovered even if one or more of its singly provided subsystems suffers an error or failure.
The invention provides the advantage, despite the use of single systems, i.e. without redundantly duplicating flight-relevant systems, of nevertheless providing a reduced risk of losing the drone. Thus not only can development and production costs be reduced, but also the costs of operating the drone can be reduced as it can carry an increased payload and/or has a reduced fuel requirement.